Definitely and interesting challenge as I usually create zentangles on the standard tiles. About the only time I draw large is when I'm teaching a class - drawing on large pad on an easel. Not quite the same.
Onamato and Gneiss appeared on the tile first but it took several attempts and false starts to finally settle on Meer as the final pattern. Shading was an added challenge. Have a couple of other Biggified tiles almost completed - feeling a little stumped on the shading.
Click on image for larger view
Biggify